Two weeks later, he ran a half-marathon. The next day, while working in his garden, Huhta felt a severe pain in the back of his head.

"It was different than a normal headache," he said. "I was light sensitive and had no strength, no appetite. I took two aspirin, went to bed and stayed there for five days. I thought I had the flu."

When Huhta finally returned to work, he couldn't speak clearly. Concerned friends took him to the hospital, where he was diagnosed as having a ruptured cerebral aneurysm.

20% Die Immediately

Huhta was lucky. Each year about 30,000 people suffer from ruptured cerebral aneurysms. And according to Dr. Neil Martin, assistant professor of neurosurgery at UCLA Medical Center, "Twenty percent of those stricken with aneurysms die immediately. Thirty percent die within a couple of weeks, and fewer than half survive without disabling neurologic problems."

Martin characterized a cerebral aneurysm as a "weakened spot in an artery in the brain that might gradually enlarge and rupture, causing bleeding into surrounding areas."

Studies have shown that aneurysms are not hereditary in most cases, nor do they have well-established risk factors. They are most common in people 30 to 60 years old and strike men and women with equal frequency.

Indeed, in some cases, symptoms are so generalized that patients are misdiagnosed.

Called a Hangover

Barbara Pope and Dorothy Haryung are well aware of this situation.

The day before her 22nd birthday, Pope was getting ready for her job at a phone company.

"I had a killer headache," Pope remembers. "It felt like someone hit me on the head with a baseball bat. I saw everything with a halo around it."

After driving to work, Pope blacked out in her car for a minute or so.

"I woke up, got out of the car and walked about 10 feet. Then I saw the pavement coming straight at my face."

A passer-by saw Pope fall between cars and summoned help.

In the emergency room at a small community hospital, Pope was told she had a hangover.

Two Surgeries

"I had had a couple drinks the night before," she said. However, later that day, when Pope failed to wake up, her mother called their doctor.

Pope eventually underwent two aneurysm surgeries, one to repair the bleeding aneurysm and one to remove a second small unruptured aneurysm on the other side of her brain.

"I didn't wake up until after the second surgery," she said.

Another patient, Dorothy Haryung, was reading the morning paper and drinking coffee when she lost vision in her right eye and had a severe pain in her left temple.

"It came on very suddenly," 69-year-old Haryung said.

She knew immediately what was wrong.

Specialists Argued Over Her

"Both my mother and grandfather had aneurysms. I certainly knew the symptoms."

In the emergency room, Haryung was treated by an ophthalmologist and a neurologist.

"The ophthalmologist said there was a nerve involved and that I should take cortisone for a year. The neurologist thought it was carotid artery disease and wanted to do an endarterectomy. Both of them were fighting over me.

"I wouldn't buy it."

A few days later, Haryung's husband took her to another hospital, where she was properly diagnosed and operated on.

Headaches Are Typical

Huhta, Pope and Haryung all experienced one key symptom of a ruptured aneurysm--a severe headache.

Said UCLA's Martin: "A sudden, severe headache is always present. It is strongest on one side of the head or behind the eye or the back of the neck." He said the symptoms are not vague, and the headache is abrupt and "can get better over hours or in one to two days."

Moreover, the headache may be accompanied by nausea and vomiting, light sensitivity, a generalized aching and a stiff neck.

Many patients have no symptoms until their aneurysms rupture and they incur the abrupt symptoms listed above.

However, some physicians believe that almost 50% of patients have warning signs before their aneurysms rupture. These could be caused by a minor leak from the aneurysm or by the aneurysm pressing on surrounding structures in the brain. Early signs include a headache, weakness, a dilated pupil or a strange noise heard in the head.

Diagnosis Difficult

"Early diagnosis and detection of aneurysms is a real problem," said Dr. Steve Giannotta, associate professor of neurosurgery at USC School of Medicine. "Sometimes the warning signs are so subtle that you can't expect anyone to pick them up. Sometimes they are so non-specific that you can't prove they are warning signs."

Giannotta estimates that 5% to 10% of patients don't receive immediate help because they are misdiagnosed. Martin and Giannotta agree that educating the public and physicians about the warning signs of aneurysms is an essential step toward early diagnosis.